mmc: allow host claim / release nesting

This change allows the MMC host to be claimed in situations where the host
may or may not have already been claimed.  Also 'mmc_try_claim_host()' is
now exported.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Matt Fleming <matt@console-pimps.org>
Cc: Ian Molton <ian@mnementh.co.uk>
Cc: "Roberto A. Foglietta" <roberto.foglietta@gmail.com>
Cc: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Cc: Denis Karpov <ext-denis.2.karpov@nokia.com>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: Philip Langdale <philipl@overt.org>
Cc: "Madhusudhan" <madhu.cr@ti.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 7ac8b500d55c..e4898e9eeb59 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -139,6 +139,7 @@ extern unsigned int mmc_align_data_size(struct mmc_card *, unsigned int);
 
 extern int __mmc_claim_host(struct mmc_host *host, atomic_t *abort);
 extern void mmc_release_host(struct mmc_host *host);
+extern int mmc_try_claim_host(struct mmc_host *host);
 
 /**
  *      mmc_claim_host - exclusively claim a host
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 338a9b3d51e4..631a2fea5264 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -182,6 +182,8 @@ struct mmc_host {
         struct mmc_card         *card;          /* device attached to this host */
 
         wait_queue_head_t       wq;
+        struct task_struct      *claimer;       /* task that has host claimed */
+        int                     claim_cnt;      /* "claim" nesting count */
 
         struct delayed_work     detect;